problem: motion blurring using glAccum

I''m trying to get motion blurring to work for my game engine. It''s a racing game, so I want the car to blur when it''s going really fast. Here''s a general outline of what I''m doing: within my draw function I 1. draw the objects in the scene 2. use glAccum(GL_MULT, .8); 3. glAccum(GL_RETURN, 1.0); which doesn''t work. Is this because I''m not really accumulating any frames on top of each other, which would give a blurring effect? Unlike the examples I''ve seen, I''m not drawing a stationary object, moving it and drawing it to the accum buffer, and returning it (swapping it to the color buffer). Is that where I''m going wrong? Maybe I''m not sure what glAccum(GL_MULT, value) does exactly. Could someone clarify what it''s actually doing, please? It''s drawing the scene, then it''s multiplying each value (R, G, B, A) of the accum buffer by the constant I specify, then returns the accum buffer to the current color buffer that''s being written to. When does the scene that was rendered before calling glAccum come in to play? Any help and/or explanations would be greatly appreciated. Thanks, Jessica